sed command

The flags can be any of the following:

g

replace all matches

Example: echo "aaaaa" | sed -e 's/a/b/g' ==> bbbb
 

n

replace nth instance of pattern with replacement

p

write pattern space to STDOUT if a successful substitution takes place

w file

Write the pattern space to file if a successful substitution takes place 

Example_ Capitalize the first letter

’s/./\u&/g’